title: Detection and characterization of CD133+ cancer stem cells in human solid tumours.
abstract: BACKGROUND
  Osteosarcoma is the most common primary tumour of bone. Solid tumours are made of heterogeneous cell populations, which display different goals and roles in tumour economy. A rather small cell subset can hold or acquire stem potentials, gaining aggressiveness and increasing expectancy of recurrence. The CD133 antigen is a pentaspan membrane glycoprotein, which has been proposed as a cancer stem cell marker, since it has been previously demonstrated to be capable of identifying a cancer initiating subpopulation in brain, colon, melanoma and other solid tumours. Therefore, our aim was to observe the possible presence of cells expressing the CD133 antigen within solid tumour cell lines of osteosarcoma and, then, understand their biological characteristics and performances.
  
  
  RESULTS
  In this study, using SAOS2, MG63 and U2OS, three human sarcoma cell lines isolated from young Caucasian subjects, we were able to identify and characterize, among them, CD133+ cells showing the following features: high proliferation rate, cell cycle detection in a G2\M phase, positivity for Ki-67, and expression of ABCG2 transporters. In addition, at the FACS, we were able to observe the CD133+ cell fraction showing side population profile and forming sphere-clusters in serum-free medium with a high clonogenic efficiency.
  
  
  CONCLUSIONS
  Taken together, our findings lead to the thought that we can assume that we have identified, for the first time, CD133+ cells within osteosarcoma cell lines, showing many features of cancer stem cells. This can be of rather interest in order to design new therapies against the bone cancer.
authors.affiliation: Dipartimento di Medicina Sperimentale, Sezione di Istologia ed Embriologia, Seconda Università degli Studi di Napoli, Napoli, Italy.
authors.forename: Virginia
authors.initials: V
authors.lastname: Tirino
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Desiderio
authors.forename: Riccardo
authors.initials: R
authors.lastname: d'Aquino
authors.forename: Francesco
authors.initials: F
authors.lastname: De Francesco
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pirozzi
authors.forename: Antonio
authors.initials: A
authors.lastname: Graziano
authors.forename: Umberto
authors.initials: U
authors.lastname: Galderisi
authors.forename: Carlo
authors.initials: C
authors.lastname: Cavaliere
authors.forename: Alfredo
authors.initials: A
authors.lastname: De Rosa
authors.forename: Gianpaolo
authors.initials: G
authors.lastname: Papaccio
authors.forename: Antonio
authors.initials: A
authors.lastname: Giordano
mesh_terms: D000071916:AC133 Antigen; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000032:analysis; D015703:Antigens, CD; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002469:Cell Separation; D005434:Flow Cytometry; D016195:G2 Phase; D006023:Glycoproteins; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D009363:Neoplasm Proteins / Q000032:analysis; D014411:Neoplastic Stem Cells / Q000473:pathology*; D012516:Osteosarcoma / Q000473:pathology*; D010455:Peptides
chemical_list: C116614:ABCG2 protein, human; D000071916:AC133 Antigen; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D015703:Antigens, CD; D006023:Glycoproteins; D019394:Ki-67 Antigen; D009363:Neoplasm Proteins; C000606023:PROM1 protein, human; D010455:Peptides